This morning the Israel Defense Forces operation in the Gaza Strip approaches a critical juncture: To be − deeper in, at a higher cost − or not to be. The operation in its current format has exhausted itself. There is no point in pursuing it. The choice now is between going forward, at a price Israeli society is understandably reluctant to pay, or stopping, completing the mission in place and undertaking a unilateral withdrawal without waiting for the false hope of an agreement without Hamas' participation. Additional achievements cannot be expected without further efforts that could prove too late and too great.

Last night's blast, which killed three Israeli troops and wounded about 20 others, was a hint of what could happen if the ground operation is expanded. The IDF is advancing slowly and carefully in the northern Gaza Strip. Israelis, and especially those with loved ones risking their lives in battle, should be grateful to the entire chain of command for their caution. The commanders endanger themselves no less than their soldiers, as last night's events demonstrated.

The troops' measured advance is aimed at giving them superiority in every engagement with Hamas. Israel knows that Hamas seeks the blood of IDF soldiers, Israeli civilians and Palestinians not a party to the conflict. The IDF seeks to minimize the damage to these three groups and maximize it among a fourth group − Hamas members.

The operation is largely meeting its aims on that score, but it has still not achieved its goal. After one and a half weeks of fighting the operation is experiencing tension between the immediate goals and ultimate objectives. The immediate goals are destroying rocket launchers, killing fighters and arresting wanted men for interrogation and to swap for Gilad Shalit. The ultimate objectives are a lasting and stable cease-fire, and a long-term end to arms smuggling into Gaza.

This tension includes the inherent differences among the three highest-ranking entities behind the operation: the political echelon, and within it the conflicts among the Olmert-Barak-Livni trio; Chief of Staff Gabi Ashkenazi; and Southern Command head Yoav Galant. No subordinate rank is capable of providing the rank above it with spectacular results at a minimal effort ?(and above the cabinet is Israeli society as a whole?). We can pay little and get little, or pay a lot and get little, and perhaps − no guarantees − we can pay a lot and get a lot.

As things stand now, Israel will find it hard to translate its military power into policy gains. As long as Hamas can fire into Be'er Sheva and north of the Israel Air Force base at Hatzor, the organization will not submit to Israel's cease-fire terms, despite the hits it has taken.

Operation Cast Lead's table of contents currently has two chapters. The first was the air campaign. The second was the movement of ground forces.

The IDF now faces two main military alternatives. The first is to step up the confrontation with Hamas in Gaza City and its environs. That will entail greater casualties among our soldiers, increase the hardships of the Palestinian population and lead to more calls from the international community to stop the fighting.

The second option is to expand the theater of operations and strive for a target that has not yet been set, which has been concealed or even denied: to bring down the Hamas government. Southern Command is capable of achieving this goal but is not enthusiastic about it, lest the Jabalya refugee camp turn into Somalia. In this context the IDF is afraid of being too successful.

In both cases it will take days before the cabinet that sent in the IDF is able to claim a lasting victory.

In these circumstances, with the IDF attempting to maneuver between two prohibitions − against bringing down Hamas on the one hand, and reaching an agreement with it on the other − Israel is dependent on the mercy of Hamas to allow it to declare victory. For that reason Hamas must agree to a coexistence in Gaza − of the Hamas government, stripped of its rockets; the forces of Palestinian President Mahmoud Abbas along the Philadelphi Route ?(the two battalions trained in Jordan by the United States?); and perhaps also an inter-Arab or international force at the border crossings.

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